It’s no longer called FSR, it’s now “Sharp” scaling filter.

To enable it, the game first needs to be running at a lower resolution than the display. You can either set the resolution lower than 1280/800 in game settings or in steam properties for that specific game. Once you’re in the game, press the QAM button (the “. . .” button), go to performance menu (circle with a lightning bolt), enable advanced view, then scroll down to the bottom. There’s “Scaling Mode” and “Scaling Filter”.

Scaling mode controls how it stretches the screen:

• auto - keeps the aspect ratio (max of x2 scaling)
• integer - scales while preserving pixel ratio, this makes it the best option for pixel art games
• fill - will fill the whole screen while keeping aspect ratio the same. If the game isn’t 16:10 ratio, it will clip off part of the video.
• stretch - fill whole screen, stretch to fit. Ignores aspect ratio, so can distort image.
• fit - preserves aspect ratio, scales to screen (like auto but no max scaling amount I think)

Scaling filter controls how it scales the game up:

• Linear - basic scaling, minimal performance impact
• Pixel - use this for pixel art games
• Sharp - previously called FSR, will add detail and sharpen the image. When you enable this, it will also add a sharpness slider beneath the scaling filter slider. Using this when upscaling to a much higher resolution display (like a 4k TV) can cause a noticeable performance hit, I recommend capping the max external display resolution to 1080p in the Steam>Display settings if you notice performance issues with this.